﻿472 
  PROCEEDINGS 
  OF 
  THE 
  GEOLOGICAL 
  SOCIETY. 
  

  

  2. 
  The 
  Sand-bed. 
  — 
  This 
  division 
  presents 
  the 
  following 
  varieties 
  : 
  

   sometimes 
  it 
  is 
  a 
  rather 
  compact 
  red 
  or 
  yellowish 
  -red 
  sandstone, 
  at 
  

   others 
  soft 
  and 
  loose 
  ; 
  green 
  and 
  black 
  grains 
  are 
  more 
  or 
  less 
  inter- 
  

   mixed, 
  and 
  one 
  or 
  both 
  often 
  predominate, 
  giving 
  a 
  complex 
  and 
  

   almost 
  variegated 
  appearance 
  to 
  the 
  deposit 
  ; 
  or 
  the 
  red 
  and 
  yellow 
  

   sand 
  may 
  be 
  replaced 
  by 
  the 
  brown- 
  and 
  black-grained 
  sand, 
  which 
  

   passes 
  imperceptibly 
  into 
  the 
  Marl, 
  and 
  as 
  gradually 
  into 
  the 
  

   Coralline 
  stratum 
  of 
  the 
  Upper 
  Limestone. 
  

  

  The 
  red 
  or 
  yellowish-red 
  variety 
  is 
  the 
  most 
  regular, 
  and 
  abounds 
  

   with 
  fossils, 
  which 
  are 
  nsnally 
  found 
  in 
  a 
  high 
  state 
  of 
  preservation. 
  

   Lenticulites 
  complanatus, 
  Defr., 
  in 
  certain 
  situations, 
  enters 
  largely 
  

   into 
  its 
  composition. 
  Beautiful 
  specimens 
  of 
  Ctyjoeaster 
  alius 
  and 
  C. 
  

   marginatus, 
  also 
  the 
  magnificent 
  Urchin 
  Conoclypus 
  plagiosomus, 
  

   are 
  by 
  no 
  means 
  rare. 
  Remains 
  of 
  Delphinus 
  and 
  Manatus 
  have 
  

   been 
  found 
  ; 
  also 
  teeth 
  of 
  eight 
  or 
  ten 
  distinct 
  species 
  of 
  Squcdidce, 
  

   palate-teeth 
  and 
  spines 
  of 
  gigantic 
  Rays, 
  &c, 
  with 
  Cetacean 
  

   bones, 
  the 
  flat 
  fragments 
  of 
  the 
  latter 
  having 
  been 
  mistaken 
  for 
  

   fossil 
  wood. 
  The 
  thickness 
  of 
  this 
  formation 
  is 
  veiy 
  variable. 
  I 
  

   have 
  seen 
  cliff-sections 
  not 
  exceeding 
  4 
  feet 
  in 
  thickness, 
  whilst 
  in 
  

   other 
  situations 
  upwards 
  of 
  50 
  feet 
  of 
  perpendicular 
  cliff 
  appears 
  

   above 
  ground. 
  

  

  3. 
  The 
  Marl. 
  — 
  This 
  bed 
  does 
  not 
  merit 
  the 
  name 
  of 
  clay, 
  inas- 
  

   much 
  as 
  it 
  is 
  never 
  met 
  with 
  free 
  from 
  carbonate 
  of 
  lime. 
  It 
  is 
  a 
  

   mistake 
  to 
  suppose 
  that 
  fewer 
  organic 
  remains 
  are 
  met 
  with 
  in 
  

   the 
  Marl 
  than 
  in 
  other 
  Maltese 
  deposits. 
  The 
  only 
  difference 
  is 
  

   that 
  in 
  the 
  latter 
  they 
  are 
  found 
  in 
  an 
  imperfect 
  state 
  of 
  preservation, 
  

   and 
  crumble 
  to 
  pieces 
  on 
  exposure 
  to 
  the 
  atmosphere. 
  The 
  fossils 
  

   are 
  incrusted, 
  and 
  the 
  original 
  substance 
  is 
  replaced 
  by 
  peroxide 
  of 
  

   iron 
  (not 
  iron 
  pyrites, 
  as 
  stated 
  by 
  Capt. 
  Spratt 
  in 
  his 
  Notes). 
  

  

  In 
  this 
  way 
  several 
  perishable 
  substances 
  have 
  been 
  preserved, 
  

   such 
  as 
  the 
  bone 
  of 
  a 
  small 
  Cutde-Jlsh, 
  and 
  fragments 
  of 
  a 
  Nautilus. 
  

   Nodules 
  of 
  sulphur 
  are 
  rare. 
  

  

  Beautiful 
  specimens 
  of 
  crystalline 
  and 
  lamellar 
  gypsum 
  abound. 
  

   The 
  rents 
  and 
  cracks 
  of 
  the 
  Upper 
  Limestone 
  give 
  ready 
  access 
  to 
  rain, 
  

   which, 
  with 
  the 
  weight 
  of 
  the 
  limestone-strata, 
  causes 
  the 
  Marl 
  to 
  

   fall 
  and 
  become 
  piled 
  up 
  in 
  great 
  heaps, 
  which 
  appear 
  to 
  best 
  

   advantage 
  in 
  cliff-exposures, 
  wdiere 
  they 
  look 
  as 
  if 
  they 
  had 
  been 
  

   carted 
  over 
  the 
  cliffs. 
  The 
  extensive 
  denudations 
  seen 
  all 
  over 
  this 
  

   Island 
  are 
  evidently 
  the 
  result 
  of 
  the 
  perishable 
  nature 
  of 
  this 
  bed, 
  

   which 
  has 
  been 
  completely 
  washed 
  away 
  in 
  the 
  east 
  and 
  north-east 
  

   of 
  Malta 
  ; 
  perhaps 
  during 
  the 
  gradual 
  upheaval, 
  or 
  by 
  the 
  wear 
  and 
  

   tear 
  of 
  the 
  elements 
  during 
  the 
  long 
  unreckoned 
  ages 
  which 
  have 
  

   since 
  elapsed. 
  

  

  4. 
  The 
  Calcareous 
  Sandstone. 
  — 
  According 
  to 
  Capt. 
  Spratt 
  (op. 
  cit.) 
  

   there 
  are 
  five 
  varieties 
  of 
  this 
  bed, 
  but, 
  from 
  a 
  close 
  study 
  of 
  its 
  

   characters 
  and 
  appearances, 
  I 
  do 
  not 
  find 
  this 
  classification 
  hold 
  good, 
  

   inasmuch 
  as 
  the 
  different 
  sorts 
  blend 
  so 
  much 
  into 
  one 
  another, 
  and 
  

   are 
  so 
  variable 
  as 
  to 
  positive 
  conformity, 
  &c, 
  that 
  any 
  attempt 
  at 
  

   defining 
  the 
  appearance 
  or 
  distribution 
  of 
  one 
  or 
  the 
  other, 
  far 
  less 
  

   their 
  thickness, 
  must 
  be 
  considered 
  fallacious 
  in 
  a 
  great 
  degree. 
  It 
  

  

  